Black Hole Bonanza: StarTalk Live! With Janna Levin and Jenny Greene

How do supermassive black holes form? Neil deGrasse Tyson and comedian Chuck Nice come to you live to learn about the history of black holes, what’s inside them, and new discoveries with cosmologist Janna Levin and astrophysicist Jenny Greene.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:01Neil deGrasse Tyson?

  Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now.

• 0:14Neil deGrasse Tyson?

  Philadelphia, we are back at the Keswick Theater. StarTalk Live!

• 0:27Neil deGrasse Tyson?

  And now, we're gonna talk about black holes. And I have some expertise in black holes, but not enough to fill the length of this show. So we combed the landscape for my colleagues, who spend their lives thinking about black holes. We found one of them at Princeton University, not even that far up the street. As far as distances go, welcome to the stage Jenny Green, professor of astrophysics. Jenny, there she goes.

• 1:08Neil deGrasse Tyson?

  She's otherwise known as the Black Hole Hunter. We're gonna find out what that means. So you study supermassive black holes, and how to find them, and where they're located in the universe. So you're a black hole hunter. And you also... She is faculty director of the Prison Teaching Initiative at Princeton. This is... Princeton has a program where faculty go to the prison and teach. You teach algebra? So that the prisoners can come out with some kind of a degree? And reduce the recidivism? Yes! We salute you! Next, another black hole expert.

• 1:52Neil deGrasse Tyson?

  One of our favorites, she's a regular on StarTalk, really. And she is professor of physics and astronomy at Barnard and Columbia University. Jan Levin! So, just so we understand the context here, we have Jan Levin, who approaches this problem of black holes as a physicist. And she's interested in cosmology, spacetime continuum, and the like.

• 2:18Neil deGrasse Tyson?

  Whereas, we otherwise are searching for actual black holes in the actual universe. And so, these are two sides of the same coin that we're going to explore this evening. So, let's do this. I know you're all fans of science, you wouldn't be here otherwise, but let's make sure we're on the same page. Okay? Tell us what a black hole is.

• 2:42Chuck Nice?

  Oh, that's a good thing to know.

• 2:43Neil deGrasse Tyson?

  I was not pointing to you Chuck. Chuck, my face.

• 2:46Chuck Nice?

  I didn't want to ask myself.

• 2:47Neil deGrasse Tyson?

  Chuck, my.

• 2:48Chuck Nice?

  I was just like, you know, I was just like, oh, when are they gonna get to this part?

• 2:53Speaker 02

  You should always ask.

• 2:53Neil deGrasse Tyson?

  Exactly.

• 2:54Speaker 02

  Always ask.

• 2:55Neil deGrasse Tyson?

  Yeah, so Jenny, tell us, just give us the basics of a black hole.

• 2:57Speaker 02

  So, a black hole is an object with so much mass, in such a small space, that not even light can escape its gravitational pull.

• 3:07Neil deGrasse Tyson?

  So is it fair to say that the escape velocity, which is the speed necessary to leave an object forever, on Earth, I memorized all these, on Earth it's 7 miles per second. So Chuck, that old saying that your grandmother said, what goes up must come down?

• 3:22Chuck Nice?

  Right, not true.

• 3:23Neil deGrasse Tyson?

  Not true.

• 3:23Chuck Nice?

  My grandmother was dumb as hell.

• 3:27Neil deGrasse Tyson?

  She just didn't have intro physics.

• 3:29Chuck Nice?

  This is true, right.

• 3:31Neil deGrasse Tyson?

  So if you can throw faster than 7 miles per second, it will leave Earth and never come back to Earth. Okay, and so, the sun has an even higher escape velocity as you might expect. So a black hole, the escape velocity, is it fair to say it's greater than the speed of light?

• 3:44Speaker 02

  Even going at the speed of light, you could not escape the gravitational pull of a black hole.

• 3:49Neil deGrasse Tyson?

  So I'm on Earth, I toss something up and it comes back. If I take a beam of light on the black hole, and turn on the flashlight, what happens to the beam of light?

• 3:58Janna Levin?

  Ooh, I love that one.

• 3:59Chuck Nice?

  Oh, that is cool.

• 3:59Janna Levin?

  You can actually get it to hang there, forever.

• 4:02Neil deGrasse Tyson?

  Light with hang time.

• 4:03Janna Levin?

  So, the region that Jenny is talking about, beyond which not even light can escape, is known as the event horizon. And it's just a demarcation line, there's nothing there.

• 4:12Neil deGrasse Tyson?

  Is there a nice poetic term for something that'll just kill you? The event horizon?

• 4:17Chuck Nice?

  No, no.

• 4:18Neil deGrasse Tyson?

  The event horizon.

• 4:19Chuck Nice?

  Exactly.

• 4:20Speaker 02

  Because it sounds innocent.

• 4:21Janna Levin?

  You have to say it's smoky light. But if you release a little pulse of light exactly at the event horizon, it will try to race outward at the speed of light. But you can think of the event horizon as a region where spacetime is falling inward like a waterfall at the speed of light. And so it just sits there.

• 4:41Chuck Nice?

  Oh, look at that. Oh, my God. You just described my marriage.

• 4:50Janna Levin?

  Good thing this isn't going to be on TV or anything.

• 4:53Chuck Nice?

  Don't worry, she's here.

• 4:55Neil deGrasse Tyson?

  Wait, so Janet, you wrote a book called The Black Hole Survival Guide, which is a little scary because you should not come close enough to a black hole to ever have to think about surviving it, is what I'm thinking.

• 5:07Janna Levin?

  Yeah, spoiler alert, it doesn't end well.

• 5:09Neil deGrasse Tyson?

  Yeah, OK. So you described, you said that black holes are nothing.

• 5:16Janna Levin?

  Yeah.

• 5:17Neil deGrasse Tyson?

  They are no thing.

• 5:18Janna Levin?

  Yeah, they're not a thing.

• 5:20Chuck Nice?

  They're not a thing.

• 5:21Janna Levin?

  They're not a thing.

• 5:22Chuck Nice?

  Why are we here?

• 5:23Janna Levin?

  Why are we here?

• 5:26Janna Levin?

  You can, you can think of a black hole, in some sense, as a place. It's a place, it's a region in space, as you've said, beyond which not even light can escape. But that, that region, that event horizon, has left like an archaeological record on the spacetime. The thing that formed the black hole, maybe it's a collapsing star, it can no more sit at the event horizon than it can race outward at the speed of light. So once it gets, collapses under its own weight and it forms this region where everything goes dark, it is forced to continue to collapse and leave behind an empty space with nothing in it.

• 6:06Chuck Nice?

  It's a prisoner of itself. Oh.

• 6:09Neil deGrasse Tyson?

  So its gravity created its own cage, in a sense.

• 6:12Janna Levin?

  Yeah, and, and when the star forms it, it is forced to disappear as well down the black hole. The black hole, it, it's like dispenses with the star. So whatever made it is gone. So if you go up to that edge of the event horizon, it's as undramatic as stepping into the shadow of a tree. There's nothing there.

• 6:32Neil deGrasse Tyson?

  So when people think of a black hole as a solid object, clearly it's not.

• 6:35Janna Levin?

  It is not.

• 6:35Neil deGrasse Tyson?

  It's a region of space.

• 6:36Janna Levin?

  Yes, it's a place.

• 6:38Neil deGrasse Tyson?

  A region of space. Okay, so what's some background on this? Jenny, can you tell me, when did the black hole physics come online?

• 6:48Speaker 02

  Well, so one of the really cool things to me is that when I learned about gravity in high school.

• 6:54Neil deGrasse Tyson?

  We went to the same high school. Not at the same time, because I'm an old fart, but we went to the same, the Bronx High School of Science.

• 7:00Chuck Nice?

  Mm-hmm.

• 7:01Neil deGrasse Tyson?

  We are both from the Bronx in the house today.

• 7:03Speaker 02

  Where I learned that gravity was a force of attraction because objects have mass. But light doesn't have mass. So there's this magical thing that it's actually bending in space and time, which light also moves through space and time and so knows the effects of gravity. So the very first thing was we had to have this idea of general relativity.

• 7:24Neil deGrasse Tyson?

  General relativity, so that's Albert Einstein, your favorite man?

• 7:26Janna Levin?

  My favorite?

• 7:27Neil deGrasse Tyson?

  Yeah.

• 7:28Janna Levin?

  Yeah.

• 7:28Chuck Nice?

  You guys should know this, that there is an ongoing feud between these two, whereas, of course, Neil's man is Newton.

• 7:37Neil deGrasse Tyson?

  Yeah, Isaac Newton.

• 7:38Janna Levin?

  Yes.

• 7:39Chuck Nice?

  And her man is Einstein. And often, it's wonderful to get drunk and watch them fight about who is better.

• 7:49Neil deGrasse Tyson?

  Isaac Newton discovered the laws of optics, the laws of gravity, and, uh...

• 7:56Janna Levin?

  He also stabbed himself in the eye with a stick to test out the rods and cones.

• 7:59Neil deGrasse Tyson?

  Yeah, just as an...

• 8:00Janna Levin?

  So there was that.

• 8:02Chuck Nice?

  Doesn't sound like a genius to me.

• 8:06Neil deGrasse Tyson?

  But he did all of that and decided to invent integral and differential calculus.

• 8:12Janna Levin?

  It's pretty impressive.

• 8:12Neil deGrasse Tyson?

  Then he turned 26.

• 8:15Chuck Nice?

  Ooh.

• 8:16Neil deGrasse Tyson?

  Mic drop.

• 8:17Chuck Nice?

  Ah. All right, Jenna, your response?

• 8:22Janna Levin?

  Well, Einstein said of himself, you know, when I was a student, I was no Einstein. So he was, he was actually not a very good student.

• 8:32Chuck Nice?

  That's really cool.

• 8:35Neil deGrasse Tyson?

  All right, let me clear up a couple of things. So we needed Einstein to advance these ideas, but Einstein did not...

• 8:43Neil deGrasse Tyson?

  Even come up with the idea of a black hole. Actually, we can go farther back in time. Uh, when, uh, to the late seventeen hundreds.

• 8:52Chuck Nice?

  Okay.

• 8:52Neil deGrasse Tyson?

  There's a physicist named John Mitchell.

• 8:55Chuck Nice?

  All right.

• 8:56Neil deGrasse Tyson?

  John Mitchell, forgotten, long forgotten.

• 8:59Chuck Nice?

  He is, cuz until you said it, I still don't know who he is.

• 9:04Neil deGrasse Tyson?

  John Mitchell wondered, once the speed of light had been established, he wondered, could a star be so massive that the light cannot escape and that the star turns dark? And he called them dark stars. So this is the brilliant, even before Einstein and before he had the math tools to do this, he advanced this concept. And, oh, by the way, John, John Mitchell, I, I have on here in my notes, what I think is fascinating. He, all his work was forgotten. No one knew about this. He had to be rediscovered.

• 9:44Chuck Nice?

  Clearly, nobody knew, not, nobody here knows about him.

• 9:47Neil deGrasse Tyson?

  Okay, there's no picture of him. And he was described by someone, this is fascinating, in, in England, of having, he was black of complexion.

• 9:58Chuck Nice?

  Oh.

• 10:01Chuck Nice?

  Okay, so either he had bubonic plague,

• 10:05Chuck Nice?

  or he was a black man.

• 10:06Neil deGrasse Tyson?

  Okay.

• 10:09Neil deGrasse Tyson?

  Is bubonic plague Black Death, is that right?

• 10:10Chuck Nice?

  That's the Black Death.

• 10:11Neil deGrasse Tyson?

  That's the Black Death.

• 10:12Chuck Nice?

  That's why they called it that, cuz, you know, you actually turn black.

• 10:15Neil deGrasse Tyson?

  Yeah.

• 10:15Chuck Nice?

  Which is why it gets such a bad rap.

• 10:19Neil deGrasse Tyson?

  Is that why? There's no picture of him, so we actually portrayed him in Cosmos, and we had a black actor portraying him. Just, just put him in there, didn't even mention anything about it. Uh, it was just.

• 10:31Chuck Nice?

  How fitting that a black man discovered the black hole.

• 10:35Neil deGrasse Tyson?

  Okay.

• 10:38Janna Levin?

  Behave yourself.

• 10:43Neil deGrasse Tyson?

  All right, so, uh, why do you pick this up? When we think of black holes, we think of this voracious vacuum cleaner, that whichever direction it, it just eats things up. So is that accurate?

• 11:01Janna Levin?

  Well, as we have discussed, things can't usually fall directly into a black hole.

• 11:10Neil deGrasse Tyson?

  Okay.

• 11:11Janna Levin?

  They have some energy, and so actually they tend to orbit.

• 11:18Neil deGrasse Tyson?

  Swirl.

• 11:18Janna Levin?

  Swirl.

• 11:19Neil deGrasse Tyson?

  Okay.

• 11:20Janna Levin?

  Around a black hole. And this stuff...

• 11:23Neil deGrasse Tyson?

  That doesn't sound like a very good vacuum cleaner if stuff's got to swirl first.

• 11:27Chuck Nice?

  But it does sound like an awesome toilet.

• 11:29Neil deGrasse Tyson?

  Okay, so this whole thing that black holes suck, the way a vacuum cleaner... This is wrong.

• 11:33Janna Levin?

  It's very overblown. If our sun right now were to turn into a black hole,

• 11:39Neil deGrasse Tyson?

  With the mass that it currently has,

• 11:40Janna Levin?

  With the mass that it currently has, Shrink it to a black hole. Some evil genius comes along, figures out how to shrink it to a black hole. It becomes 6 kilometers across. It's a really tiny little thing. Our orbit would be...

• 11:50Neil deGrasse Tyson?

  It's America with 6 kilometers.

• 11:56Chuck Nice?

  I'll tell you what it is. None of my damn business.

• 12:01Neil deGrasse Tyson?

  So about 4 miles across.

• 12:02Janna Levin?

  I've lost miles a long time.

• 12:04Neil deGrasse Tyson?

  You've lost a long time.

• 12:05Janna Levin?

  Yeah, so it would fit inside New York City.

• 12:08Neil deGrasse Tyson?

  Okay.

• 12:10Janna Levin?

  Our orbit would be just fine. So we would no more be sucked into a black hole than we are sucked into the sun. There would be very little detectable difference in terms of the Earth's orbit. We'd be perfectly fine. So this is a completely overblown hysteria.

• 12:23Neil deGrasse Tyson?

  We would rapidly freeze to death.

• 12:25Janna Levin?

  That would be bad.

• 12:26Neil deGrasse Tyson?

  Okay, so don't say we'll be fine.

• 12:31Janna Levin?

  The Earth would be fine. The Earth would just keep right on...

• 12:34Neil deGrasse Tyson?

  As a planetary object.

• 12:35Janna Levin?

  As a planetary object. The rock would persist in its orbit. We would be gone.

• 12:39Neil deGrasse Tyson?

  And all life on Earth. But there is life that thrives undersea that absorbs energy from undersea vents, which is leftover heat from the formation of Earth. So depending on your age in the audience, I am of that age, we learned that from our biology textbooks that all life on Earth requires sunlight to survive. Take away the sunlight, we'd all die. That's before we had discovered this life form thriving at the bottom of the ocean, that are part of what we call extremophiles. Life forms that do the backstroke.

• 13:12Chuck Nice?

  Where the sun don't shine.

• 13:13Neil deGrasse Tyson?

  Where the sun don't shine, right. And so, just to be clear, yeah, surface life would rapidly die.

• 13:20Janna Levin?

  Yeah, you gotta get really close to a black hole is the point. Really, really close. This thing's only six kilometers across. You gotta get within like 20 kilometers of it. I mean, you're right on top of it.

• 13:29Neil deGrasse Tyson?

  Which I have no intent of doing.

• 13:31Janna Levin?

  Yeah, and don't do it to the sun either. Because that would also.

• 13:34Chuck Nice?

  Yeah, that would be so bad. That would be bad. I'm gonna ask that you guys stop speaking in metric terms.

• 13:41Neil deGrasse Tyson?

  No, you could, um, NASA did a research study. They found that you can send astronauts to the sun, provided you visit at night.

• 13:53Neil deGrasse Tyson?

  Just saying. Uh, Jana, why? If Einstein invented the framework to understand and even predict black holes. A, why didn't he predict black holes?

• 14:07Janna Levin?

  He did not, that's right.

• 14:08Neil deGrasse Tyson?

  And or why? And when he learned about them, why was he in denial of them?

• 14:12Janna Levin?

  Yeah, so he gets a letter from a friend who's an astronomer who has enlisted in, uh, uh, the German infantry. He's a German infantry soldier during World War I. And he's on the Russian front during the war. And the apocryphal story is that between calculating ballistic trajectories in the war, he's reading the proceeding of the Prussian Academy of Sciences.

• 14:36Neil deGrasse Tyson?

  Is this Carl Schwarzschild?

• 14:36Janna Levin?

  As you do, Carl Schwarzschild. In which Einstein has published his final description in mathematical terms. You know, he nails it. General relativity, the theory of curved spacetime. And Carl Schwarzschild does this little thought experiment. He says, imagine the entire mass.

• 14:53Neil deGrasse Tyson?

  While people are shooting at him.

• 14:54Janna Levin?

  While people are shooting at him, yeah. He's, uh, yeah, in the trenches hiding and calculating. And he does this beautiful thought experiment. He says, imagine you crush the entire mass of a star to a point. He doesn't ask how this is possible or how nature could do such an absurd thing. That's not really of interest to him initially. He just says, imagine it. And then he asks of Einstein's equations to reveal to him what the nature of the curved spacetime is as a result of that. And he writes down.

• 15:21Neil deGrasse Tyson?

  So this is a thought experiment?

• 15:22Janna Levin?

  It's a thought experiment.

• 15:23Neil deGrasse Tyson?

  With the math, very good.

• 15:24Janna Levin?

  Yeah, with the math. And he writes down the first description that has in it an event horizon, a region beyond which not even light can escape. And it has all the descriptions of the spacetime around a black hole. Einstein's very impressed by this. He couldn't believe it's six months. After Einstein publishes his theory. And he thinks this is terrific. He helps him get it published. But Einstein thinks, you know, nature's going to protect us from their formation. After all, how are you possibly going to crush a star to a point? And so he doesn't think that they're going to be real. He thinks they're a mathematical...

• 15:57Neil deGrasse Tyson?

  He thinks some new law of nature yet to be discovered is going to save his ass.

• 16:00Janna Levin?

  Well, there are lots of laws that were there. Like, I can't crush this glass to a point. It's really hard. It resists pressure. You know, there's matter has pressure.

• 16:10Chuck Nice?

  If you were a real housewife, you'd be able to do that.

• 16:15Janna Levin?

  I mean, it was sensible.

• 16:19Janna Levin?

  I wouldn't do that over a glass of water. Exactly. There was sensible reason to believe that matter would resist being crushed.

• 16:26Neil deGrasse Tyson?

  Okay. So this is not sensible reason. I would call it a bias. A bias that he had because he didn't think nature would do that. Okay. So now, when did we have our first evidence of a black hole?

• 16:39Janna Levin?

  Well, we had our first evidence of black holes, I believe, in the 20s.

• 16:43Neil deGrasse Tyson?

  Okay. So when did we first figure out that we had evidence of a black hole? 1970. So this is 50 years, 60 years after Einstein. Okay. So what's this famous bet between Stephen Hawking and not an Einstein? What was it? And Kip Thorne? Remind us who Kip Thorne is?

• 17:04Janna Levin?

  Kip Thorne is a very brilliant relativist. His, a lot of his work as a scientist was in the area of curved spacetime. Big Bang, black holes, wormholes, that sort of thing. He won the Nobel Prize recently, fairly recently, in the past few years, for his work...

• 17:21Neil deGrasse Tyson?

  2020.

• 17:22Janna Levin?

  Yep. In discovering or theorizing about the collision of two black holes ringing spacetime like a drum. And when it was eventually observed, a project that he was involved in for more than 50 years, he received the Nobel Prize along with his collaborators. And he's also wrote the treatment for Interstellar.

• 17:40Neil deGrasse Tyson?

  The movie. The movie Interstellar.

• 17:42Chuck Nice?

  He was a slacker.

• 17:45Neil deGrasse Tyson?

  Only wrote the treatment. He was listed as executive producer of the series. Do you remember? Did you guys see Interstellar? Okay. Wait, who has not seen Interstellar? Okay, security could...

• 17:58Chuck Nice?

  Notice they didn't clap.

• 18:00Neil deGrasse Tyson?

  No, they didn't clap.

• 18:02Chuck Nice?

  The people who saw it were like, "Yeah!" Like, who has not seen it? I'm okay.

• 18:08Neil deGrasse Tyson?

  By the way, those who remember it, there's a robot in it. That had these sort of funky rectangular legs.

• 18:13Chuck Nice?

  Yeah.

• 18:14Neil deGrasse Tyson?

  Do you remember the name of that robot? No? Well, there were several, but the lead one was called Kip. It was called Kip. This robot was Kip. After Kip Thorne. That's how you get your situation in the situation.

• 18:26Chuck Nice?

  I remember that, because he told him to turn down the humor, and I was like, "I'm done with this movie."

• 18:31Neil deGrasse Tyson?

  All right, so there was a bet between Stephen Hawking and Kip Thorne. Yeah. About this, whether or not we actually had the data justified for a black hole. So what was the first black hole?

• 18:44Speaker 02

  Well, I know it was a stellar mass black hole, so 10-ish suns with a star friend, and the black hole is slowly eating material from the star.

• 18:59Neil deGrasse Tyson?

  So the black hole is flaying the star. Okay.

• 19:02Chuck Nice?

  So they should call them vampire holes. For real.

• 19:06Neil deGrasse Tyson?

  Yeah. So I remembered, because this swirling material that you began describing earlier can get very hot and start radiating in a form of light that you get when you have very hot gas, such as X-rays. And so when we first had X-ray telescopes, we started discovering these sources of X-rays that didn't, there was nothing else obvious happening in that region of space. And one of them was a strong X-ray source in the constellation Cygnus. And so it was sensibly called Cygnus X1. So I remember, I was alive, because that's how old I am, when that was discovered, we were very excited. We read all about it.

• 19:49Neil deGrasse Tyson?

  Is that still to this day a confirmed black hole?

• 19:52Speaker 02

  Yeah.

• 19:53Neil deGrasse Tyson?

  Yeah. Look at me like, "Yeah, okay, sorry."

• 19:56Janna Levin?

  But it is worth pointing out that that doesn't mean we could see the black hole. Like, you couldn't resolve the black hole. You were deducing that the object that was emitting this incredibly high energy, you could tell, had a certain amount of mass and was very, very small. And you deduce from that that it's a black hole. But all you could see were the X-rays. So you couldn't see the black hole itself. And I think this surprised people to learn that we really didn't see a black hole from many decades.

• 20:23Chuck Nice?

  Let me just understand this, and I'm serious when I'm asking this. Are you saying that the X-rays were emanating from the black hole? Is that the black hole is spewing out X-rays?

• 20:35Janna Levin?

  It's emanating from around the black hole. From around the black hole.

• 20:38Speaker 02

  It's this stuff that's trying to fall into the black hole.

• 20:41Neil deGrasse Tyson?

  Don't you learn anything? They said nothing comes out of a black hole.

• 20:43Chuck Nice?

  And that's my point. So how are you seeing something when nothing can escape it? How are you seeing anything around it? That's what I want to know.

• 20:49Janna Levin?

  It's because this reputation of black holes sucking up everything is overblown. Things can live very close to the event horizon of a black hole, be very hot, and you do a lot of work on this.

• 21:00Neil deGrasse Tyson?

  And what's happening in those discs?

• 21:01Chuck Nice?

  This stuff is swirling around it.

• 21:02Speaker 02

  It wants to get into the black hole, but it has some energy, right? And so it can't just fall right in. So what nature does is it forms...

• 21:09Neil deGrasse Tyson?

  It has orbital energy.

• 21:10Speaker 02

  It has orbital energy, that's right. It forms these discs, accretion discs. And what happens in the disc is that the gas cozies up with itself. It gets really nice and close.

• 21:20Chuck Nice?

  And it gets hot.

• 21:20Speaker 02

  It gets hot. It rubs against itself, it gets hot. And this is super exciting for astronomers because how astronomers study the universe is by gathering light.

• 21:29Chuck Nice?

  Right.

• 21:30Speaker 02

  And so without that stuff near the black hole, we wouldn't have found them.

• 21:34Chuck Nice?

  So we're not seeing anything from the black hole itself. All we're seeing is what's happening around the black hole. And that excited material that gets all like, "Hey, man, we about to go to a black hole, man."

• 21:50Neil deGrasse Tyson?

  About to die.

• 21:50Chuck Nice?

  It's crazy. And then it gets hot and it gets excited. And then we see that as light, and that's how we know.

• 21:57Neil deGrasse Tyson?

  Of high-energy wavelengths.

• 21:58Chuck Nice?

  High-energy wavelength.

• 21:59Neil deGrasse Tyson?

  Yes. And so it gets...

• 22:01Chuck Nice?

  What the hell is wrong with you people? That is amazing.

• 22:05Chuck Nice?

  I just learned something. I don't know about you, but that is amazing.

• 22:08Neil deGrasse Tyson?

  Okay, wait.

• 22:08Chuck Nice?

  That is amazing!

• 22:10Neil deGrasse Tyson?

  So what's raising?

• 22:11Chuck Nice?

  We see nothing! And we know everything from seeing nothing!

• 22:20Neil deGrasse Tyson?

  Okay. Chuck just blew a gasket. We gotta bring him, we gotta repair Chuck.

• 22:23Chuck Nice?

  This is why I love doing this show, I'm sorry. This is, this is why I do it. That's amazing. Go ahead, I'm sorry.

• 22:29Neil deGrasse Tyson?

  Okay, Chuck will be in for repairs this weekend. So, this friction is the gas spiraling down, losing that energy that it had, and it's gotta end up slow enough to drop in.

• 22:42Janna Levin?

  It's circling the drain.

• 22:44Neil deGrasse Tyson?

  The drain.

• 22:45Janna Levin?

  Yeah.

• 22:45Neil deGrasse Tyson?

  The toilet bowl. So, this friction, you've done this in cold weather, but you can just do it now. Rub your hands, it doesn't take much rubbing to feel the temperature of your hands go up. Just do it, you know the result, but just try it.

• 22:58Chuck Nice?

  First clap 'em, and then do that.

• 23:03Neil deGrasse Tyson?

  Okay, so, so...

• 23:04Chuck Nice?

  And then go heal somebody.

• 23:08Chuck Nice?

  First you clap, then you rub.

• 23:10Neil deGrasse Tyson?

  Yeah.

• 23:10Chuck Nice?

  And now you're healed.

• 23:12Neil deGrasse Tyson?

  I told you Chuck needs repairs.

• 23:16Neil deGrasse Tyson?

  Alright, so was there a bet and who won it? Who'd bet on what?

• 23:19Janna Levin?

  Oh, so, okay, so...

• 23:20Neil deGrasse Tyson?

  Stephen Hawking and Kip War.

• 23:22Janna Levin?

  Kip is the loveliest guy, and he, he's, he's a straight shooter. He's gonna vote for the black hole. And Stephen was a bit of a trickster, and had this kind of a nimical quality to him.

• 23:34Neil deGrasse Tyson?

  She's on first-name basis.

• 23:35Janna Levin?

  Oh, Stephen.

• 23:36Neil deGrasse Tyson?

  With Stephen Hawking.

• 23:37Janna Levin?

  Oh, that's so obnoxious, I'm sorry. Hawking was a bit of a trickster, and so his, he bet against black holes, even though so much of his life had been devoted to understanding them. I think he also suspected they were, that they were observing a black hole, but he just wanted to, you know, he, he wanted to bet the, I don't know.

• 23:57Neil deGrasse Tyson?

  Be the antagonist.

• 23:58Janna Levin?

  Be the opposition, be the antagonist, be the devil's advocate. So, yes, he bet against Kip, but he did capitulate pretty early on. And I think the story is he, he broke into Kip's office at Caltech, or some such.

• 24:09Chuck Nice?

  Wait, Stephen Hawking did this?

• 24:10Janna Levin?

  Yeah.

• 24:13Neil deGrasse Tyson?

  What point in his life would...

• 24:19Neil deGrasse Tyson?

  That's a detail left out of the story.

• 24:22Chuck Nice?

  I'm just trying to...

• 24:22Neil deGrasse Tyson?

  We'll let that one go.

• 24:23Chuck Nice?

  I'm just saying.

• 24:24Neil deGrasse Tyson?

  We'll let that one go, okay. So, he, he rappelled down the building?

• 24:30Chuck Nice?

  I mean, I would believe it. Because I would leave it up to Stephen Hawking to figure out a way to rappel down a building. You know.

• 24:39Janna Levin?

  Yeah, to break into Kip's office, yeah.

• 24:40Neil deGrasse Tyson?

  Okay. And so, then what happened when he broke into the office?

• 24:43Janna Levin?

  Well, I think he left him a note conceding.

• 24:45Neil deGrasse Tyson?

  Okay.

• 24:46Janna Levin?

  Conceding the bet, yeah.

• 24:48Neil deGrasse Tyson?

  Okay, so that's odd for him to be anti-black hole because because of his intellect, we know so much about black holes. So one of them is like, black holes are not forever. So what do black holes do when left to their own devices?

• 25:03Janna Levin?

  Well, okay, so this is a very subtle issue because Chuck already raised it. The black hole lets nothing from the inside out again. But Hawking figured out this very clever way. The black hole could kind of steal energy from empty space. And I don't think you want me to get into this whole thing because this is a whole big thing. But but there's this possibility that empty space sort of, you know, has this frothing quantum foam that's sort of.

• 25:28Chuck Nice?

  Oh, that's got into the quantum.

• 25:30Janna Levin?

  And it is only when Hugh introduced the quantum that this happens, only then. And he figured out a way that the black hole could steal a little from the empty space.

• 25:40Neil deGrasse Tyson?

  What you're saying is Newton gravity, Einstein gravity alone doesn't get you this result.

• 25:45Janna Levin?

  Does not.

• 25:46Neil deGrasse Tyson?

  He has to bring in quantum physics.

• 25:47Janna Levin?

  Absolutely, yeah.

• 25:49Neil deGrasse Tyson?

  Which is the physics of the small.

• 25:50Janna Levin?

  Yeah.

• 25:51Neil deGrasse Tyson?

  To describe something that's going on in the physics of the large.

• 25:54Chuck Nice?

  And for you children out there, sometimes when Newton gravity really loves Einstein gravity.

• 26:03Chuck Nice?

  They get together and they make a quantum.

• 26:07Neil deGrasse Tyson?

  So so it's is this when we hear that black holes evaporate?

• 26:11Janna Levin?

  So what happens is the black hole ultimately evaporates. It actually gets less massive and it exposes something in the vacuum that has to radiate away. So it doesn't come from inside the black hole, but it's in tandem with this quantum process. But what it looks like from afar is it looks like the black hole is evaporating. It is emitting particles at a hot temperature and it is getting smaller in the process.

• 26:36Neil deGrasse Tyson?

  When I first learned this, you know what freaked me out? And maybe it'll blow another gasket for Chuck. When I first learned this, it was like, wait a minute. It is spontaneously creating particles out of the gravitational field outside of the event horizon, outside of the event horizon. So the energy there spontaneously becomes matter. The matter escapes and the mass of the black hole drops. So what's inside the event horizon loses mass to stuff that's happening outside the event horizon.

• 27:13Janna Levin?

  Yeah.

• 27:13Neil deGrasse Tyson?

  All right, I gotta go smoke some weed.

• 27:23Janna Levin?

  That's exactly right. It essentially absorbs what we would consider to be a negative energy particle in favor of emitting a positive energy particle. You could say something like negative energies don't exist, but because of the relativity of space and time inside the black hole, you don't think it's a negative energy. You think it's a negative momentum. And so it's completely consistent with the laws of physics.

• 27:44Neil deGrasse Tyson?

  I'm leaving with Chuck right now.

• 27:48Chuck Nice?

  No, that is dope. What you just described is what Harry Potter would call magic.

• 27:54Neil deGrasse Tyson?

  So where did the term "black hole" come from?

• 27:57Janna Levin?

  Oh, so that's a great story because Schwarzschild didn't call it a black hole. Einstein didn't call it a black hole. It was 1967, I believe, and the great John Wheeler, who was the kind of granddaddy of all of relativity in America.

• 28:08Neil deGrasse Tyson?

  And a student of Einstein.

• 28:09Janna Levin?

  He trained Kip Thorne. Yeah, a student of Einstein's and he trained Kip Thorne and Richard Feynman and all of these great people. He was onstage near Columbia, like above Tom's Diner, you know, from Seinfeld. And giving a lecture. It wasn't Tom's Diner, I don't believe, in the 1967. And he kept saying the end state of catastrophic gravitational collapse over and over again. And apparently, from the back row, somebody shouted, "How about black hole?" And he just took it and foisted it on all of us. And one day, he wrote something to the effect like "The Cheshire Cat, the star fades from view. One leaves behind only its smile. The other leaves behind only the black hole."

• 28:54Janna Levin?

  I butchered that a little bit, but it's something like that. And with that usage, it was on us.

• 28:59Chuck Nice?

  I just feel bad for the guy who yelled it out.

• 29:02Chuck Nice?

  Because nobody will never know who he is. And he came up with the actual name.

• 29:08Neil deGrasse Tyson?

  Jenny, you focus on supermassive black holes. And...

• 29:13Neil deGrasse Tyson?

  You know, we bandy about the word "super" so often that it almost loses meaning. I'd like you to sort of give it, give its strength and presence once again. So, what's a supermassive black hole? What's an ordinary black hole? Is there a mini black hole? What is the mass range and where do we find these beasts?

• 29:35Speaker 02

  Yeah, so usually when we say "supermassive", we're thinking about million suns. That's the black, our own black hole at the center of the Milky Way.

• 29:43Neil deGrasse Tyson?

  So when we say "million suns", you mean, take the mass of a million of our suns and cram it into one object to make a black hole? A million!

• 29:50Speaker 02

  A million.

• 29:51Neil deGrasse Tyson?

  And by the way, if the sun were hollow, you could pour a million Earths into it.

• 29:57Chuck Nice?

  So a million, a million.

• 29:59Neil deGrasse Tyson?

  Million, million.

• 29:59Chuck Nice?

  A million, million is what a supermassive black hole is.

• 30:02Neil deGrasse Tyson?

  Correct, okay.

• 30:03Speaker 02

  The low end, they can be a trillion. Yeah, so the friend we talked about earlier, where we saw the base of the jet, M87, we know we've seen a picture of its event horizon. That's a billion. So when I was a kid, we also had the Sig X-1s of the world. These are like the mass of the sun, but a bit bigger, so maybe 10 suns. Now LIGO, we've seen black holes, or we've heard black holes merging.

• 30:29Neil deGrasse Tyson?

  LIGO is the abbreviation of the telescope, the Gravity Telescope that Kip Thorne pioneered, Laser Interferometry Gravitational Wave Observatory. Okay, so go on.

• 30:41Chuck Nice?

  And where's the "W"? See, every time y'all say that, I'm like, "There's no W." But, never mind, go ahead.

• 30:48Speaker 02

  Astronomers love their acronyms. Don't let real words get in the way.

• 30:53Neil deGrasse Tyson?

  One's called "ligwo." All right, fine, go ahead.

• 30:57Speaker 02

  So, so for all time, it was 10 suns and then a million suns. And one of the amazing things for me as an astronomer that LIGO has taught us is that it's actually, these stellar mass black holes go all the way up to 100 suns at least. But that still leaves a big space between 100 and 100,000 or a million, and we just have no idea. We just don't know.

• 31:23Neil deGrasse Tyson?

  Okay, so we don't even know what mechanism could create such an object?

• 31:28Speaker 02

  Well, so with the 10-ish sun black holes.

• 31:31Neil deGrasse Tyson?

  That's just a dead fat star.

• 31:33Speaker 02

  That is the death of a star, yes. And then these things up to 100, they seem to be probably the mergers of those.

• 31:42Neil deGrasse Tyson?

  Okay.

• 31:43Speaker 02

  Right? Well, we see them merging.

• 31:45Neil deGrasse Tyson?

  That's, that, Chuck, you see what she did there? It's like, we don't even know how to make those, so let's add the others together, and that's how you get there.

• 31:51Janna Levin?

  But LIGO has detected 30 and 30, or 60 and 30 merging to the 100 range.

• 31:56Neil deGrasse Tyson?

  I get that, but we don't know how to make those, so you just staple together the ones that are 10 solar mass. Is that what you're doing?

• 32:02Speaker 02

  Well, not with the supermasses.

• 32:04Janna Levin?

  Not with a staple gun.

• 32:07Chuck Nice?

  You guys are witnessing your first science fight.

• 32:11Neil deGrasse Tyson?

  Like nerd fight. All right, so, so I just admit, we don't know what could make a 30 to 100 solar mass black hole.

• 32:18Janna Levin?

  No, no, 30 to 100 you can, but a million, we don't know. A million, we have no idea.

• 32:22Neil deGrasse Tyson?

  But you haven't detected a million yet.

• 32:24Janna Levin?

  Yeah, like the supermasses at the center of our galaxy, 4 million. No way is a million. 4 million. 4 million. 3.0, yes.

• 32:30Neil deGrasse Tyson?

  4 million, okay. When we come back, we will resurrect this argument about how massive the black holes are, and what in the universe is making them.

• 32:40Chuck Nice?

  Not the size matters.

• 32:44Neil deGrasse Tyson?

  On StarTalk.

• 32:54Speaker 04

  Hi, I'm Chris Cohen from Hallworth, New Jersey, and I support StarTalk on Patreon. Please enjoy this episode of StarTalk Radio with your and my favorite personal astrophysicist, Neil deGrasse Tyson.

• 33:17Neil deGrasse Tyson?

  We're back for segment two at the Kestwick Theater in Philadelphia. All right.

• 33:26Neil deGrasse Tyson?

  StarTalk Live.

• 33:30Neil deGrasse Tyson?

  I got with me Janna Levin, black hole extraordinary expert and Jenny Green, a professor at Princeton University. All right. So in this segment, we want to spend a little more time on detecting the undetectable. And of course, you know, our friend, the one with black complexion, gave us, gave a first indication, John Mitchell, of how you might detect it.

• 34:01Chuck Nice?

  Mm-hmm.

• 34:02Neil deGrasse Tyson?

  And that was if a star is black, dark.

• 34:06Chuck Nice?

  It will get pulled over by the star police

• 34:11Chuck Nice?

  in a second.

• 34:14Chuck Nice?

  Do you know why I stopped you? I was not doing faster than the speed of light.

• 34:20Chuck Nice?

  That would be impossible.

• 34:23Neil deGrasse Tyson?

  But we clocked you at 1.5 the speed of light.

• 34:28Neil deGrasse Tyson?

  The speed of light, not, it's not just a good idea, it's the law.

• 34:33Neil deGrasse Tyson?

  Yeah.

• 34:36Neil deGrasse Tyson?

  Nah, I don't even remember where I was here. What, what? Oh, Mitchell, thank you. So he's, he's supposed, because by then we knew that there were stars that were double, they were double stars. More than half the stars you see in the night sky come in at least pairs, and in some cases triples and even entire clusters. So the isolated star is not even all that common. And the only, I would say, single correct science out of all 30 Star War movies, Star Wars movies, uh, was in the first Star Wars One, which I think they call Star Wars Part Four.

• 35:16Chuck Nice?

  That's right.

• 35:17Neil deGrasse Tyson?

  Where they show Luke was at the sand planet and he comes out and there's a double sunset.

• 35:21Chuck Nice?

  Right.

• 35:22Neil deGrasse Tyson?

  On the horizon.

• 35:22Chuck Nice?

  Yeah.

• 35:23Neil deGrasse Tyson?

  And I said, somebody finally did this. Uh, and so more power to the people who thought that up.

• 35:30Chuck Nice?

  That's the only thing they got right.

• 35:32Neil deGrasse Tyson?

  That's the only thing they got right in the entire series. Just thought I'd put that out there.

• 35:38Neil deGrasse Tyson?

  You want to fight, meet me outside. We'll, we'll, after school.

• 35:44Neil deGrasse Tyson?

  So what he said, so if you just see a star doing loop-de-loops, and there's, and you don't otherwise see anything there, then something dark has gravity and is tugging on it. So let's, so Jenny, pick us up from there. All right, now, we left off when we began with the, with this jets and the thing, and all this stuff, and Chuck blew a gasket, hearing that we still can't see black holes. We got an hour and a half show on black hole, and we still can't see them. So what are the clever ways that ingenious astrophysicists have come up with to detect them?

• 36:18Speaker 02

  Right, so this is why I'm on Team Newton. Because almost all the ways that we find black holes actually don't even need general relativity. It's just Newton's laws, right?

• 36:27Neil deGrasse Tyson?

  Like I said, Jen.

• 36:30Janna Levin?

  I'm, I'm gonna be the one waiting for you outside.

• 36:34Speaker 02

  Right, so the star friend of Sig X1, we can watch it going around Sig X1, and we can figure out there must be a really dense object there, just like planets going around the sun. We can figure out the mass of the black hole. And in fact, we can do the same for the black hole at the center of our own galaxy, um, Sag A star, and...

• 36:55Neil deGrasse Tyson?

  So there's a black hole, so the Milky Way has its own black hole?

• 36:58Speaker 02

  We have our own supermassive black hole. We have lots and lots of stellar mass black holes.

• 37:03Neil deGrasse Tyson?

  And we agreed that's four million times...

• 37:05Speaker 02

  Four million suns.

• 37:06Janna Levin?

  And the thing about black holes is that they're spatially small. So that's less than 20 times the width of the sun, but it's four million times the mass. So picture the sun on the sky, you know, don't stare at the sun, but like, picture the sun in the sky. Imagine just, you know, 20 times across, and this thing is...

• 37:24Neil deGrasse Tyson?

  And then cram a million suns.

• 37:26Janna Levin?

  Four million.

• 37:27Speaker 02

  Four million.

• 37:28Neil deGrasse Tyson?

  One million suns.

• 37:28Janna Levin?

  And then push it... Yeah, and then push it 26,000 light-years away, and it's like a tiny, teeny little thing on the sky. So it's about as big on the sky as people liken it to a piece of food on the moon. So it's really tiny, and that's why black holes are so challenging. Because despite their heft, they're spatially small.

• 37:49Neil deGrasse Tyson?

  So, so, small and hefty.

• 37:54Neil deGrasse Tyson?

  All right, so we have this range...

• 37:55Chuck Nice?

  There are many jokes I'm not doing right.

• 38:00Neil deGrasse Tyson?

  So this, so I'm of the age where black holes in the centers of galaxies was a new idea. We found them in one galaxy and then another random other galaxy. And as we do in my field, if you find it in this galaxy and that galaxy, then all galaxies must have it. That was the driving presumption. And sure enough, when Hubble came online, it had good views down in the centers of galaxies. And bada bing, we have yet to find a galaxy that does not have a supermassive black hole. Is that correct?

• 38:33Speaker 02

  Uh.

• 38:33Neil deGrasse Tyson?

  I guess not, okay?

• 38:34Speaker 02

  That's not correct.

• 38:34Neil deGrasse Tyson?

  Sorry.

• 38:38Neil deGrasse Tyson?

  Meet me outside. We'll settle this in the parking lot.

• 38:42Speaker 02

  What's the... Big galaxies, big galaxies like our Milky Way or M87.

• 38:47Neil deGrasse Tyson?

  Yes.

• 38:48Speaker 02

  So far as we know, they all are most.

• 38:51Neil deGrasse Tyson?

  Isn't that what all I was saying?

• 38:52Chuck Nice?

  Wait, here's the real question. Have we found galaxies where there are not supermassive black holes?

• 38:57Neil deGrasse Tyson?

  Big galaxies.

• 38:58Chuck Nice?

  Big ga... no, yes, yeah.

• 38:59Neil deGrasse Tyson?

  Red blooded gal... American galaxies.

• 39:01Chuck Nice?

  Yeah, murk. Like, like the kind of galaxy you would put in the back of a cosmic pickup truck.

• 39:07Neil deGrasse Tyson?

  Yeah, a pickup truck with a gun rack.

• 39:09Chuck Nice?

  That's right.

• 39:09Neil deGrasse Tyson?

  We got one of those?

• 39:11Speaker 02

  We have smaller galaxies that don't have black holes. Is it, is it possible they were... We have not yet asked for their passports, so we can try that.

• 39:19Neil deGrasse Tyson?

  All right, all right, okay, I got you. All right, so now this galaxy, one of the most massive galaxies in our catalogs, is in the Virgo cluster, supercluster of galaxies. Because galaxies cluster the way stars cluster.

• 39:33Chuck Nice?

  They're very clickish.

• 39:34Neil deGrasse Tyson?

  That's, that's the, the universe just doing its thing with gravity. So we have the Virgo supercluster, has thousands of galaxies. The most massive galaxy in that is in the Messier catalog. Messier was a French astronomer in the 1700s.

• 39:50Chuck Nice?

  And an awesome hockey player.

• 39:54Neil deGrasse Tyson?

  He wanted to make a catalog of fuzzy objects in the night sky so that you don't confuse them for comets that you might be trying to discover. So it's called the Messier Catalog. And this is this, it's really the catalog of not comets. But it turned out to be a catalog of the most famous fuzzy objects in the night sky, including Messier 87, which is this supermassive galaxy. It's far enough away, it's just a smudge of light, but it's got trillions of SARS. So, we recently, the astronomical community, recently published a photograph of that black hole. Tell me about it.

• 40:37Speaker 02

  We can actually see light swirling around the event horizon. Because astronomers are incredible at working together to build these pictures. And as Jana said, it's a piece of fruit on the moon.

• 40:55Neil deGrasse Tyson?

  In terms of angular size.

• 40:56Speaker 02

  In terms of how big it is in the sky.

• 40:58Neil deGrasse Tyson?

  So, so I've heard there's something called the Event Horizon Telescope. So that lets you think there's like one telescope sitting somewhere looking for a black hole. But what is it actually?

• 41:08Speaker 02

  So it's a network of telescopes. And what's important for getting a tiny, tiny picture is that you put your telescopes as far apart as possible so that you can get this really, really high angular resolution.

• 41:22Neil deGrasse Tyson?

  So you're not getting different sets of data? In principle, you're getting one coherent set of data? As though the telescope were as wide as the diameter of the Earth?

• 41:33Speaker 02

  Basically, although you have to work really hard to make it coherent.

• 41:37Neil deGrasse Tyson?

  A bunch of cameras taking the same picture. And you, and you get the resolution of something as wide as Earth? As though your telescope were that size?

• 41:44Speaker 02

  As though your telescope were that size. But in fact, you have all of these different telescopes you're coordinating. They each have detectors that somebody had to build and commission.

• 41:53Neil deGrasse Tyson?

  I looked at a list of the collaborators, and I'm like, what? Because in it, I'm like, I cannot believe they let George on here.

• 42:03Neil deGrasse Tyson?

  Look, there are countries that historically, and even today, were at war with one another.

• 42:12Neil deGrasse Tyson?

  Yet the scientists are collaborating. Can you comment on that?

• 42:15Chuck Nice?

  That deserves applause. I don't know who wanted to applaud.

• 42:19Neil deGrasse Tyson?

  Yeah.

• 42:19Chuck Nice?

  Somebody started applauding, but yes, that deserves applause. Because, quite frankly, only these guys can absolutely hate each other, but love science so much, that they will continue to work together. And that should be a model for the rest of us to follow.

• 42:40Neil deGrasse Tyson?

  Right, right. The geopolitics of the world.

• 42:42Chuck Nice?

  It should be.

• 42:45Janna Levin?

  So, the Nobel Prize in Physics, which includes prizes for astronomy, can only be awarded to three people or less. And there has been sort of a discussion, I don't know how seriously it was taken, that the Nobel Peace Prize should be given to major scientific collaborations. Because they are working both across things like the Large Hadron Collider, the James Webb Space Telescope, the Event Horizon Telescope. These are examples of what human beings can do if we put our minds to it.

• 43:16Neil deGrasse Tyson?

  As a model for geopolitics.

• 43:18Janna Levin?

  Yeah.

• 43:19Neil deGrasse Tyson?

  Yeah, interesting.

• 43:23Neil deGrasse Tyson?

  So you'd simply open up the Peace Prize to not only the usual things that might earn it, but then the collaborations that transcend governments.

• 43:32Janna Levin?

  That are demonstrations of it.

• 43:33Chuck Nice?

  Okay. We got the message.

• 43:37Neil deGrasse Tyson?

  All right.

• 43:40Neil deGrasse Tyson?

  So I want to get back to, to this jet we first started talking about. So, so we get this disk, accretion disk, which is officially called around a black hole. By the way, when I think of accretion disk, I kind of think of

• 43:58Neil deGrasse Tyson?

  a middle accretion disk around my equator. The middle-aged man.

• 44:02Chuck Nice?

  Why, are you eating accretions?

• 44:05Neil deGrasse Tyson?

  No.

• 44:07Neil deGrasse Tyson?

  So, so, okay, we got through that and we rubbed our hands and we figured this out. But now we have jets. So what's, tell me about jets.

• 44:15Janna Levin?

  I, I will tell you this about jets.

• 44:19Neil deGrasse Tyson?

  I like that she leaned in on that one.

• 44:20Chuck Nice?

  Yeah.

• 44:21Neil deGrasse Tyson?

  Grab the drink.

• 44:22Chuck Nice?

  And before you do, let me tell you about jets. When you're a jet, you're a jet all the way.

• 44:29Chuck Nice?

  From your first cigarette to your last dying day. Okay, sorry. Go ahead.

• 44:35Neil deGrasse Tyson?

  All right, so tell me about the jet. So I have these accretion discs. How do we get a jet out of that?

• 44:40Speaker 02

  Well, I guess the exciting and beautiful thing is we don't really know.

• 44:45Neil deGrasse Tyson?

  Oh, okay.

• 44:46Speaker 02

  It's got something to do with the black hole. The black hole's got a lot of energy. There are these particles that are accelerated. We think we're getting the energy from the black hole to power the jet. But I'll tell you what, when I go to meetings about black holes and accretion, the jet session is when I leave to go see the European town that I'm visiting.

• 45:11Janna Levin?

  That was a big confession. That was like a public confession.

• 45:16Neil deGrasse Tyson?

  That was the most elegant diss I've ever heard.

• 45:19Janna Levin?

  That was called good.

• 45:23Speaker 02

  For 30 years, we've been talking about how to accelerate jets and we just don't know.

• 45:28Janna Levin?

  But I do think that the irony is that what the black hole is basically doing is it's acting kind of like an electromagnetic battery. So there are these magnetic fields that are threaded through the accretion discs that the black hole can't do on its own. It needs that stuff around it. And then the churning of the spacetime due to the black hole actually basically creates a gigantic battery which starts to power these jets. So these jets are electromagnetically powered. And so black holes go from being the darkest phenomena conceivable, as we discussed in the beginning, to the largest sources of electromagnetic power in the universe that we can see at the edge of the universe.

• 46:07Chuck Nice?

  So is this an overload of this electromagnetic battery that it just can't contain all the energy that is being generated inside this accretion disc? And all of a sudden it's just like, it accelerates the particles. They get excited and they're just like, "I'm out of here!"

• 46:24Janna Levin?

  Well, literally, it's churning up the magnetic fields. And then the magnetic fields are literally like wires in a circuit. And the charges are currents.

• 46:32Chuck Nice?

  Blowing them out like currents.

• 46:33Janna Levin?

  They're currents flying out on the circuit.

• 46:35Chuck Nice?

  This is why science is awesome!

• 46:41Chuck Nice?

  That's the second thing I learned tonight. That's amazing.

• 46:44Speaker 02

  It is amazing.

• 46:46Neil deGrasse Tyson?

  Chuck just blew a third gas on that. So Jenny, what, what, tell me about your work with the James Webb Space Telescope. We've all been enchanted and, and stupefied by the beauty and majesty and its access to previously untouchable parts of the universe.

• 47:03Speaker 02

  So it's really life-changing. I would say it's like a once in a career experience it's been for me to see the James Webb data.

• 47:11Neil deGrasse Tyson?

  Okay, cool. All right.

• 47:13Speaker 02

  So as, as we said, we said there are stellarish mass black holes and there are supermassive black holes and then we don't know how to make the supermassive black holes, but we figure they must have started out smaller, somewhere in this intermediate mass black hole regime where we can't find any. But for my whole career, I've been saying, if we can find these intermediate mass black holes, we can understand how supermassive black holes form. And I've been saying, we're never gonna find them back near the big bang early in the universe because we just don't have the telescopes. So let's look for them nearby. And that's been most of my career. And now all of a sudden, we put this, you know, six-meter gold-plated thing into space

• 47:57Speaker 02

  and we are, honest to God, we're finding the baby black holes.

• 48:00Chuck Nice?

  You're finding baby black holes?

• 48:02Speaker 02

  Oh my God, are they cute?

• 48:05Speaker 02

  They are so cute.

• 48:08Chuck Nice?

  Are they like Grogu? Are they like little baby Yodas?

• 48:12Speaker 02

  I don't know how you would feel if you saw the spectra, but when I see it, I'm like, oh.

• 48:17Neil deGrasse Tyson?

  So you're reacting not to a photo of the black hole, you're reacting to a spectrum of the energy emitted in the vicinity of the black hole.

• 48:25Speaker 02

  Right, it's the, it's the secretion disk again.

• 48:27Neil deGrasse Tyson?

  And you just are touched. It warms your...

• 48:30Speaker 02

  It looks, it looks like the data that...

• 48:32Chuck Nice?

  I gotta tell you, Anna sounds like you're being catfished.

• 48:38Speaker 02

  I really, really hope not.

• 48:43Neil deGrasse Tyson?

  Yeah, so these black holes, you say they're baby black holes. That implies they're young, but are they actually young or are they just small?

• 48:51Chuck Nice?

  Ooh.

• 48:51Speaker 02

  Well, so all

• 48:53Chuck Nice?

  It's Neil.

• 48:54Speaker 02

  All the black holes are young because we're seeing them, you know, just a few million years after the Big Bang, right? Because James Webb

• 49:01Neil deGrasse Tyson?

  Okay, so everything is that age?

• 49:03Speaker 02

  Everything is young, yes, they're all adolescents back then.

• 49:06Chuck Nice?

  Oh, that's kind of dope.

• 49:08Neil deGrasse Tyson?

  Okay. Because as we see farther out in space, we look farther back in time.

• 49:13Chuck Nice?

  Right.

• 49:14Neil deGrasse Tyson?

  So we see things not as they are, but as they once were.

• 49:19Chuck Nice?

  Oh, that sounds so romantic. Now I feel like looking back at my life.

• 49:27Neil deGrasse Tyson?

  All right, so this has stoked your career.

• 49:29Speaker 02

  Yeah.

• 49:30Neil deGrasse Tyson?

  Wow. Okay, so you're still studying them. There's anything you can share with us about it?

• 49:36Chuck Nice?

  Anything new and exciting?

• 49:37Neil deGrasse Tyson?

  And what is Pandora's Cluster? I read about this.

• 49:39Speaker 02

  Yeah, so you already covered galaxy clusters.

• 49:42Neil deGrasse Tyson?

  Yes.

• 49:43Speaker 02

  Right, well, this is a galaxy cluster. It's got a thousand galaxies in it or something, and that means it sits in a really big dark matter halo. And we've already talked about how spacetime can bend light, right? So

• 49:58Neil deGrasse Tyson?

  Wait, pause. What's dark matter?

• 50:01Janna Levin?

  So dark matter is a form of matter that does not interact with light. It's that simple.

• 50:05Neil deGrasse Tyson?

  Okay, wrong answer. All right, what is dark matter?

• 50:09Janna Levin?

  Dark, oh, we don't know.

• 50:10Neil deGrasse Tyson?

  Thank you.

• 50:10Janna Levin?

  Is that what you're gonna say?

• 50:12Speaker 02

  We walked into that one, yes, thank you.

• 50:14Neil deGrasse Tyson?

  It's not only that we don't know, we have no freaking idea.

• 50:18Janna Levin?

  I would say we have a little bit of an idea because we do know that it acts like matter and we do know it doesn't interact with light. And we know that there are things like neutrinos, which exist, which are technically dark matter, no question. And by the way, it probably shouldn't be called dark. It should be called invisible. Like, if I had a handful of it, it's not that it would be dark. It would literally be invisible. So it doesn't scatter light, it doesn't absorb light. Light goes right through it. So we don't know what this dark matter that makes up the twenty-some percent of the energy budget of the universe.

• 50:47Neil deGrasse Tyson?

  So what you really should, but you know it has gravity. So you should call it invisible gravity.

• 50:52Janna Levin?

  Well, we know it acts like matter in its pressure Energy, you know, its equation of state of matter looks like regular matter in that sense.

• 51:02Neil deGrasse Tyson?

  Okay.

• 51:02Janna Levin?

  So it's implicated as particles.

• 51:04Neil deGrasse Tyson?

  All right.

• 51:05Janna Levin?

  Whereas dark energy is not particulate, presumably. And also, we don't know what that is either. And also, it's not dark, it's also invisible.

• 51:12Neil deGrasse Tyson?

  This sounds like a case for a science Angela Lansbury.

• 51:17Janna Levin?

  Okay, dark, so dark matter halo.

• 51:20Neil deGrasse Tyson?

  So you've got this cluster in the middle of a dark matter halo.

• 51:23Speaker 02

  So we have James Webb already in incredibly powerful telescope.

• 51:28Neil deGrasse Tyson?

  Yes.

• 51:28Speaker 02

  But we use the power of gravitational lensing to make it even more powerful. So because this invisible mass is sitting between us and the very early universe, the galaxies way back, you know,

• 51:46Speaker 02

  500 million years after the universe started.

• 51:48Neil deGrasse Tyson?

  Much farther back in time than the cluster you're studying.

• 51:51Speaker 02

  That's right, the cluster is basically right here.

• 51:54Neil deGrasse Tyson?

  Okay.

• 51:54Speaker 02

  But what we're, we're using it for its mass.

• 51:57Janna Levin?

  Mm hmm.

• 51:57Speaker 02

  And it is like a lens. It's, it's lensing these galaxies. And so we can see even smaller and even further back in time because we're using the power of gravitational lensing. We are exploiting this cluster.

• 52:10Neil deGrasse Tyson?

  Magnifying effects of Einstein's general relativity in the distortion in the fabric of space and time to see where even that telescope, the James Webb, would not have seen without that cluster, is that correct?

• 52:25Speaker 02

  Correct. So my, my colleague, Evo Labey, who runs this survey, he found, so remember, James Webb was built to see, had to have infrared vision because as the universe expands, the light gets stretched out. And so by the time it reaches our telescope, it's redder than when it left its galaxy. So we need these infrared goggles.

• 52:51Neil deGrasse Tyson?

  Just to be clear, I, I, I don't know that everyone fully appreciates that design feature of the James Webb Space Telescope. Because I remember, I'm old enough to remember when we were specking what it should do for us like no other telescope before it. And we said, we want to see galaxies being born. Well, what kind of light are they emitting? Well, they're emitting like ultraviolet.

• 53:14Neil deGrasse Tyson?

  Well, how are we gonna see it today? Well, over that time, it's gonna become infrared. So we built a telescope to detect the infrared that used to be ultraviolet at the time the galaxies were emitted.

• 53:29Chuck Nice?

  Thank God we don't have that technology for actual children.

• 53:35Neil deGrasse Tyson?

  So, so, so it's an extraordinary achievement in our understanding of the universe and the power of our technologies to make that happen. Just a shout out to the engineers that empower what we do as a, as scientists. Yes. Okay, so continue, please.

• 53:51Speaker 02

  So my colleague Evo, he's looking for baby galaxies. We have this, this lens, this magnification to help us out. And what he finds are things that are way redder than any galaxies we expect to see. And what he thinks he's found are basically universe-breaking galaxies. They seem to be way bigger, like the size of the Milky Way, already. And no one thinks there was enough time to make those galaxies, yet. How did you make all of those stars so quickly?

• 54:21Chuck Nice?

  Because it takes a certain amount of time for a galaxy to form.

• 54:23Speaker 02

  And we don't have that kind of time, yes.

• 54:25Chuck Nice?

  Actual singularity that we're talking about to begin with. So there's an incongruency in the time itself.

• 54:32Neil deGrasse Tyson?

  So these galaxies shouldn't exist in our current understanding of the early universe?

• 54:36Speaker 02

  Yeah, so it turns out, it turns out, everybody knew at the time, well, the other way-

• 54:43Neil deGrasse Tyson?

  Everybody knew.

• 54:48Chuck Nice?

  Now y'all know how I feel all the time.

• 54:52Neil deGrasse Tyson?

  Okay.

• 54:52Speaker 02

  What's the other way you can make this very red thing that seems very powerful? It seems like it's powered by lots and lots of stars, but as we've already established-

• 55:04Neil deGrasse Tyson?

  Oh, we have objects in the universe called quasars.

• 55:08Speaker 02

  Correct.

• 55:09Neil deGrasse Tyson?

  Which can, can generate intense energy in the, it's a regular galaxy, but the center of it can generate intense energy, and we think-

• 55:20Neil deGrasse Tyson?

  Some of that intensity is because it's aiming stuff at us. Is this where you guys are landing?

• 55:25Speaker 02

  Well, it's probably just a regular accretion disk, but it can make a lot more light than than stars. And so now-

• 55:33Chuck Nice?

  Because it hasn't collapsed into a black hole.

• 55:35Speaker 02

  There's a black hole in the middle.

• 55:36Chuck Nice?

  In the middle.

• 55:36Speaker 02

  And it's this, it's our hands rubbing together, that accretion disk. So we think, in fact, instead of universe-breaking galaxies, he actually found a bunch of accreting black holes early on.

• 55:49Neil deGrasse Tyson?

  Okay. All right, so I-

• 55:52Chuck Nice?

  Wait, y'all, y'all get this? That was some deep stuff, man. So, so-

• 55:58Neil deGrasse Tyson?

  Wait, wait.

• 55:58Chuck Nice?

  Look, no, because I'm serious. I just got what you're saying is like, basically, you look back, you thought you found this galaxy that was old enough to be a galaxy, but it's too close to the singularity to actually be a galaxy.

• 56:11Neil deGrasse Tyson?

  Yeah.

• 56:11Chuck Nice?

  But really, what you found were a bunch of black holes just hanging out like, yo, what you got, man?

• 56:17Neil deGrasse Tyson?

  I know.

• 56:19Chuck Nice?

  Some man like, you know, and so it's all these black holes that have gathered. And because we can't see them, what we're really seeing is all the energy that all these black holes are giving off. So it's not these-

• 56:32Neil deGrasse Tyson?

  Total galaxy.

• 56:33Chuck Nice?

  -old supernova galaxies. It's a bunch of young-ass black holes.

• 56:37Speaker 02

  Young-ass black holes.

• 56:38Chuck Nice?

  And that's what it is.

• 56:40Speaker 02

  You got it.

• 56:41Chuck Nice?

  Science!

• 56:42Neil deGrasse Tyson?

  Right. Okay.

• 56:46Neil deGrasse Tyson?

  But Chuck, I want to take a slightly different view of this.

• 56:49Chuck Nice?

  Okay.

• 56:50Neil deGrasse Tyson?

  Jenny, James Webb discovers five galaxies that don't fit our understanding of the universe. So rather than allow our understanding of the universe to break, you invented some explanation for it so we can continue to think that we understand the early universe.

• 57:08Chuck Nice?

  Oh, his is killed everything I see.

• 57:10Neil deGrasse Tyson?

  Isn't that what just happened here?

• 57:12Speaker 02

  Well, but the thing is-

• 57:13Neil deGrasse Tyson?

  Well, but, well, but, okay, what?

• 57:16Speaker 02

  We got spectra.

• 57:17Neil deGrasse Tyson?

  Oh, okay.

• 57:18Speaker 02

  Yeah.

• 57:20Janna Levin?

  So.

• 57:24Neil deGrasse Tyson?

  All right, when we come back, we're going to dive into the belly of the beast and find out what the laws of physics tell us of what could be going on inside a black hole and whether any of that physics and understanding of the spacetime continuum would even allow wormholes. When StarTalk Live at the Kestwick continues.

• 58:01Neil deGrasse Tyson?

  And now, the third and final segment of StarTalk Live at the Kestwick Theater.

• 58:13Neil deGrasse Tyson?

  Let's do this.

• 58:16Neil deGrasse Tyson?

  I am with my comedic co-host, Chuck Nice. All right, and we've got Jenny Green from Princeton. And we've got Janna Levin from Barnard and Columbia.

• 58:29Neil deGrasse Tyson?

  Two of the three of them are experts in black holes. In this segment, we're going to talk about what's inside a black hole and is there time travel? Is that possible? Is, just, let's go places that telescopes have never been. Let's go ahead and do that. So Janet, in your, in your recent book, The Black Hole Survival Guide, I know, right? Where you play, you plan, when you plan a? Yeah, what I'm saying, you clearly you build a spaceship. You going somewhere?

• 59:01Janna Levin?

  I, I'm not going to do the spoiler alert, but yeah.

• 59:03Neil deGrasse Tyson?

  But you take, you take the reader.

• 59:05Janna Levin?

  Doesn't end well, as we've described.

• 59:07Neil deGrasse Tyson?

  You take the reader on a journey towards a black hole. You cross the event horizon. Mmm. And take it into the depths. Oblivion. And she's laughing. This is sinister here.

• 59:20Chuck Nice?

  I know. It's a little sinister.

• 59:21Neil deGrasse Tyson?

  This is, I'm a little worried about this right here. Right here.

• 59:24Janna Levin?

  I'm feeling a little punchy.

• 59:25Neil deGrasse Tyson?

  Right here. All right. So tell us about that.

• 59:28Janna Levin?

  Well, we were discussing how if you cross a big enough black hole, which all, most black holes are big enough for human beings, that when you cross it, it's actually quite undramatic. You really don't notice much. There's literally a principle called no drama, which is the idea that there shouldn't be anything special happening at the event horizon. So if you did not know everything about black holes and you simply saw this shadow cast on the sky, like maybe there's a whole bright galaxy behind it and you can just see the shadow of the black hole. And you went and you approached, you would enter the event horizon and maybe not even know you had done so.

• 1:00:04Janna Levin?

  But then terrible things begin to happen.

• 1:00:07Neil deGrasse Tyson?

  This sounds very much like Thanksgiving dinner.

• 1:00:11Neil deGrasse Tyson?

  Wait, so Janet, your book is mistitled because you call it the Survival Guide, but it's really your recipe for death.

• 1:00:18Janna Levin?

  Yeah, it is, yeah, it is definitely ill-advised to actually cross the event horizon because it is a guaranteed death experience.

• 1:00:27Neil deGrasse Tyson?

  Because you're not coming back.

• 1:00:29Janna Levin?

  You're definitely not coming back.

• 1:00:30Neil deGrasse Tyson?

  And we all love, we all love.

• 1:00:32Janna Levin?

  Okay, here's a sort of way you might come back.

• 1:00:34Neil deGrasse Tyson?

  Okay. Oh, there's a way back.

• 1:00:35Janna Levin?

  There's, okay, there's a tiny way back. So we talked about hawking. And people have been arguing about this whole hawking thing for a long time. So if black holes evaporate, eventually the black hole disappears. And this event horizon, which is like this curtain blocking everything that happens inside the black hole, separating it forever from us outside. You're in, you're never coming out. No information comes out. When the black hole evaporates, it's like the curtain's been yanked up. And where did all that stuff go? And so this has been a really hotly debated topic for a long time. And you might say, it just disappeared. But, but physics doesn't allow that sort of thing. That breaks physics. And, and so people have been arguing, well, maybe the information actually does come out.

• 1:01:20Janna Levin?

  Of the black hole.

• 1:01:22Neil deGrasse Tyson?

  Information that was previously lost by having fallen into it.

• 1:01:26Janna Levin?

  Right, and the information could be that it's Neil deGrasse Tyson, and it's all your quantum numbers, and it's all the way you're organized. It's in your entire life history. And if you fell into the black hole, we would never, ever be able to get that information out, except through this really subtle magical thing Hawking discovered of the radiation. So maybe if I wait outside the black hole long enough and I collect every detail of that information that came out, I could reconstruct you from that quantum information.

• 1:01:52Chuck Nice?

  It's like every Star Trek transporter episode.

• 1:01:55Neil deGrasse Tyson?

  Yeah, okay. All right, so, so, so tell me about if you actually greet the singularity at the bottom of the black hole, then you should at some point have become spaghettified.

• 1:02:12Janna Levin?

  Yeah, well, you're the king of the spaghettification story. I mean, you tell it better than anybody. I mean, I'm not gonna Neil deGrasse Tyson you. It's your turn.

• 1:02:22Neil deGrasse Tyson?

  Should I give my account of spaghettification? All right, you guys seated? Okay, so what happens is, as I stand here on Earth, you can, you don't feel this, but you can calculate that because my feet are closer to the center of gravity of the Earth than my head is, that Earth is actually pulling on my feet more strongly than it is at the top of my head, because my feet are closer. You don't feel that difference. You can calculate it is insignificant at all. The molecular structure of my body resists that on a level that you don't even notice. Well, that's because I'm here six feet two,

• 1:03:04Neil deGrasse Tyson?

  and the radius of the Earth is 4,000 miles. All right, but now watch, we get one of Janna's small black holes, and I'm falling towards the singularity. Now my height becomes significant relative to the distance that I have left to fall. So the gravity at my feet gets stronger and stronger and stronger relative to the gravity at my head, and I begin to stretch.

• 1:03:35Neil deGrasse Tyson?

  Now initially, a stretch, who doesn't like a good stretch?

• 1:03:38Chuck Nice?

  Oh, so refreshing!

• 1:03:40Neil deGrasse Tyson?

  And then until you realize this is not stopping.

• 1:03:44Chuck Nice?

  Mm-hmm.

• 1:03:45Neil deGrasse Tyson?

  And the, these are called tidal forces.

• 1:03:48Chuck Nice?

  Yes.

• 1:03:48Neil deGrasse Tyson?

  It's the stretching force of gravity's difference from one side of you to the other.

• 1:03:53Chuck Nice?

  It's when the black hole gets medieval on your ass.

• 1:03:57Neil deGrasse Tyson?

  That's, I hadn't thought of it that way. That is totally one of those rags, you know, where they try to...

• 1:04:04Neil deGrasse Tyson?

  Yeah, the medieval times, always trying to rip you apart somehow.

• 1:04:06Chuck Nice?

  Somehow.

• 1:04:07Neil deGrasse Tyson?

  Drawn and quartered. Okay, so, you're falling in, you feel the stretching, and then you realize this is not stopping, and it's no longer comfortable. And it reaches a point where the tidal forces exceed the molecular binding forces of your flesh.

• 1:04:28Chuck Nice?

  Hmm.

• 1:04:29Neil deGrasse Tyson?

  And you split.

• 1:04:33Neil deGrasse Tyson?

  You split likely at the base of your spine. Now you are two parts falling towards the singularity. And they feel the tidal force of the black hole. And so those two parts stretch. You will probably still be alive at this point, because you don't, you have important organs, but not vital organs below your waist.

• 1:04:58Chuck Nice?

  Right.

• 1:04:59Neil deGrasse Tyson?

  So...

• 1:05:00Chuck Nice?

  It's like when you see that zebra getting eaten by the lions, and it's looking down at them like, "I can't believe y'all eating me, man."

• 1:05:10Chuck Nice?

  That's messed up, man. I can't believe that. Y'all, y'all are eating me.

• 1:05:14Neil deGrasse Tyson?

  So, so you bifurcate first into two parts, then your bottom half and upper half bifurcate again. And that next one will probably sever you at your neck. And you might survive that a little. Experiments during the French Revolution where they're just chopping heads. You might as well participate in a science experiment while they're doing this.

• 1:05:34Chuck Nice?

  Exactly.

• 1:05:35Neil deGrasse Tyson?

  That the eyes connect directly to the brain, don't require the rest of your body, right?

• 1:05:40Chuck Nice?

  He saw the whole thing coming.

• 1:05:43Neil deGrasse Tyson?

  Okay. Do all French people smoke? In your irritation?

• 1:05:48Chuck Nice?

  Of course we do. Especially when we are at the beach.

• 1:05:53Neil deGrasse Tyson?

  So, you go from two to four to eight to sixteen, thirty-two. And you bifurcate all the way down until even the molecules that previously held you together, the tidal forces end up splitting those. And you become this stream of atoms descending to this cosmic abyss. And that's not even the worst part. As you're falling in, you are being funneled down to a narrower and narrower volume of spacetime. So you're not only getting stretched head to toe,

• 1:06:37Neil deGrasse Tyson?

  you're being extruded through the fabric of spacetime like toothpaste through a tube.

• 1:06:45Neil deGrasse Tyson?

  When you step back and look at this, basically, there's no other way to describe it. You have been spaghettified.

• 1:06:58Chuck Nice?

  And the whole time that that is happening, you are hearing, "When the moon hits your eye."

• 1:07:09Neil deGrasse Tyson?

  All right, so suppose you survive your trip through the event horizon. Okay? What's this stuff, you can see the back of your head? What is that?

• 1:07:17Janna Levin?

  Oh, well, that's, that's actually...

• 1:07:19Neil deGrasse Tyson?

  Cool optical effects.

• 1:07:20Janna Levin?

  Yeah, that can even happen just outside the event horizon, actually. There's a point where if you were shining light on your face and the light was reflected off, or actually shining light in the back of your head, it was reflected off the back of your head. It could travel all the way around the black hole and you could see it. Because even the light.

• 1:07:36Neil deGrasse Tyson?

  You see the back of your head in front of you.

• 1:07:37Janna Levin?

  The light gets caught in orbit, just like the International Space Station orbits the Earth. You can put light in orbit around a black hole if you get really close.

• 1:07:44Chuck Nice?

  So it's basically the photons are orbiting around so that your eyes are receiving the same information from the back of your head that you are looking at so you could see the own back of your head.

• 1:07:58Janna Levin?

  Yeah.

• 1:07:59Neil deGrasse Tyson?

  That is so dope. I'm sorry.

• 1:08:01Janna Levin?

  But what is interesting is inside a black hole, you know, there's this whole, black holes are dark and all that lore is completely true from the outside, but black holes can be bright on the inside because the light from the entire galaxy can fall in behind you. And so as you're on your way towards a singularity, the light travels faster than you do and it can catch up to you and you can watch the entire history of the galaxy unfold sped up for you.

• 1:08:26Neil deGrasse Tyson?

  The future history.

• 1:08:27Janna Levin?

  The future history. We could watch the Earth find out what happens with the whole climate change thing.

• 1:08:34Neil deGrasse Tyson?

  Believe me, we already know.

• 1:08:37Janna Levin?

  You can watch all the stars in the galaxy expire. I mean, depending on how long you take to get down there. And so it actually is quite bright for you inside a black hole. It's like all that light gets crushed towards you as you're falling towards a singularity.

• 1:08:51Neil deGrasse Tyson?

  Wait, so it's dark in front.

• 1:08:53Janna Levin?

  It's dark outside and bright inside.

• 1:08:57Chuck Nice?

  Right. Because light can't escape, but the light is still in there.

• 1:09:01Janna Levin?

  The light can fall in.

• 1:09:02Neil deGrasse Tyson?

  So the light overtakes you. You're just falling at a rate of gravity, but the light is coming in at the speed of light.

• 1:09:07Janna Levin?

  That's right. And it's all crushed together. So you see a very bright white flash of light just as you're approaching the singularity and it's like, you know, the light at the end of a tunnel.

• 1:09:16Neil deGrasse Tyson?

  When you die, you see some light.

• 1:09:17Janna Levin?

  Right. It's like a near death experience, except it's a total death experience.

• 1:09:20Neil deGrasse Tyson?

  A total death experience.

• 1:09:22Chuck Nice?

  Is your head still attached to your body?

• 1:09:24Neil deGrasse Tyson?

  It's more like a near death about it. It's a total death experience.

• 1:09:27Chuck Nice?

  It's more like looking into the arc at rates of like, it's beautiful. And then your face melts.

• 1:09:32Neil deGrasse Tyson?

  All right. So we've gotten this far and on Einstein's gravity.

• 1:09:41Neil deGrasse Tyson?

  But we know, or at least the equations tell us, that all this matter collapses down to a singularity, which disturbed Einstein. There's gotta be something that stops it. So is this the edge of general relativity's relevance in the universe? Because aren't we dividing by zero there?

• 1:10:02Janna Levin?

  Yeah, the singularity is what it really is, is it's predicting.

• 1:10:06Neil deGrasse Tyson?

  For those who don't remember from their math class, you're not supposed to divide by zero. So we have a condition here where your equations blow up.

• 1:10:15Janna Levin?

  Yeah, you're getting an infinite curvature, infinite gravitational energy density. And I don't think anyone really believes that that's what actually happens.

• 1:10:25Neil deGrasse Tyson?

  So you have to abandon general relativity?

• 1:10:26Janna Levin?

  I think it's like general relativity is signaling its own failure. And it is saying, when you get to those high energy scales, we know that we have to invoke quantum mechanics. Because as you said, quantum is of the very small. So here you're in a very tiny, tiny region of space where the energy is very high. And there's no way you can talk about it without understanding quantum gravity. And we don't understand quantum gravity. So we know that the singularity isn't a declaration of what's true. We know that it's telling us that we need to understand quantum gravity before we'll really know what's going to happen in the center of a black hole.

• 1:10:59Neil deGrasse Tyson?

  So I have a book.

• 1:10:59Chuck Nice?

  But don't we have the same problem with the quantum that we do with black holes? Is that we can't see the quantum?

• 1:11:05Janna Levin?

  Well, you mean in the center? We can't see the quantum in a conventional human way because we're a big macro scale. But we've learned to probe the quantum in a very compelling way that we have. It is the most accurate predictions in the history of science we get from quantum mechanics that are confirmed by experiment. So it is stunning. It is something we don't really understand very well. It's very elusive, but our predictions. It's very spooky, freaky predictions. But the accuracy exceeds the accuracy of any scientific prediction in the history of human culture.

• 1:11:40Neil deGrasse Tyson?

  So if you're a betting man, you would say that at the singularity, quantum physics absorbs general relativity.

• 1:11:47Janna Levin?

  You're gonna rewrite the story. And it might rewrite the story with little things like wormholes. So it might be that as you get into, this might be a crazy idea. I actually don't think it's that crazy. But that when you get to the quantum scale inside the black hole, you realize that there are these little wormholes, quantum wormholes, that are negotiating the interior and the exterior of a black hole without traveling. Inducing faster than the speed of light travel. And, um, and in fact, one of the really spooky ideas is that, in fact, the black hole is totally made up of these quantum wormholes. And so it's like, imagine embroidering a circle, and it's, you, you look like you have this big, dark shadow,

• 1:12:30Janna Levin?

  but when you look closely, you realize it's just these tangles of thread. And so at the quantum level, we might realize that the black hole, its shadow, the event horizon, all of it is really woven out of these quantum wormholes.

• 1:12:43Neil deGrasse Tyson?

  Chuck, you got that weed ready?

• 1:12:44Chuck Nice?

  I'm telling you.

• 1:12:47Chuck Nice?

  Jesus.

• 1:12:50Chuck Nice?

  That is, that's like wild.

• 1:12:52Janna Levin?

  It is wild, and that's how the Hawking radiation would get out.

• 1:12:56Neil deGrasse Tyson?

  I got one for you. I got one for you. You ready? I ran the numbers on this because, uh, large black holes are not, on average, dense, other than the singularity, big black holes have slightly different macroscopic properties. Like, you, uh, how should I say? So, let me put it another way. If you take the mass of the universe, and then I ask it, how big a black hole would the mass of the universe make? What would be the size of that event horizon? It's the size of the horizon of the universe that we observe.

• 1:13:40Neil deGrasse Tyson?

  So, is the entire universe a black hole as seen from the outside of our event horizon? And are we simply alive, enjoying the contents of our own black hole?

• 1:13:54Chuck Nice?

  Well, we better get to enjoying it quick, because we all about to be crushed into nothing, that's for sure.

• 1:13:58Neil deGrasse Tyson?

  I'm just asking.

• 1:13:59Janna Levin?

  Well, I, I mean, it's an intriguing suggestion. I would not say the universe is a black hole, but I would say we do have an event horizon as well cosmologically. So, inside the universe, we're looking at the expansion of the universe. And there is a region which we can very well articulate around us, beyond which light will never reach us. It is also an event horizon. So the universe goes dark for us beyond that point. There are things we will never see.

• 1:14:29Neil deGrasse Tyson?

  That's everything you said about the black hole.

• 1:14:31Janna Levin?

  Yeah, that's right.

• 1:14:31Neil deGrasse Tyson?

  It's the universe a black hole.

• 1:14:33Janna Levin?

  It's still not a black hole, because we're not... The thing about a black hole is it's not just this region of space that you can travel around and paddle and survive forever. Once you cross that event horizon, that singularity is actually a point in your future. So I want to emphasize this. If I look at the black hole from the outside, I think that there's a center to it because it's spatial. I think it's round. I think there's a point in the center. That point might be the singularity. And if you fall in, maybe you could avoid it. But when you're the person falling in, your space and time have rotated so much that that singularity is actually not a point in space for you at all. It's a point in time. And that singularity is in your future. And you can no more avoid it than you can avoid flowing forward in time.

• 1:15:19Chuck Nice?

  I gotta go.

• 1:15:23Chuck Nice?

  Y'all have a good night. I hope you enjoy the rest of the conversation.

• 1:15:30Neil deGrasse Tyson?

  Wait, so, so you, you mean this literally, not just figuratively?

• 1:15:36Janna Levin?

  I mean it literally.

• 1:15:37Neil deGrasse Tyson?

  The black hole is in front of me in space.

• 1:15:39Janna Levin?

  From the outside, you see that's a point in space.

• 1:15:42Neil deGrasse Tyson?

  But as I cross the event horizon, the rotation of the coordinate system is such that the center...

• 1:15:51Janna Levin?

  Is a point in your future.

• 1:15:53Neil deGrasse Tyson?

  What I would want to think of as a position in space that I might sidestep, it's no longer a position in space. It is on my timeline, and I cannot avoid it. And I'm going to get crushed at that singularity.

• 1:16:03Chuck Nice?

  It is now an inevitability, Mr. Anderson.

• 1:16:08Neil deGrasse Tyson?

  Yes.

• 1:16:08Janna Levin?

  Exactly.

• 1:16:10Chuck Nice?

  Damn.

• 1:16:10Neil deGrasse Tyson?

  That was a quote from The Matrix, in case you didn't see.

• 1:16:15Chuck Nice?

  Yes.

• 1:16:16Neil deGrasse Tyson?

  My name is Neil.

• 1:16:23Neil deGrasse Tyson?

  Sorry. We're just geeking out here right now. So, this is spooky stuff. All right, now, I can try and get another one for you. I have a book on my shelf, co-written by Stephen Hawking. I read it and didn't completely understand it. But I do remember the pages where it said that on the other side of a black hole, an entire other spacetime opens up, as though it has birthed in another universe.

• 1:16:50Janna Levin?

  That's a really profound idea. So, what's really going on there? It's the Hawking and Ellis book, right?

• 1:16:55Neil deGrasse Tyson?

  Yes, Hawking and Ellis.

• 1:16:56Janna Levin?

  Very technical.

• 1:16:57Neil deGrasse Tyson?

  Very technical.

• 1:16:58Janna Levin?

  Beautiful book. So, what, what they did...

• 1:17:01Neil deGrasse Tyson?

  To me, it was an ugly book, because I didn't understand it. To Janet, it's a beautiful book.

• 1:17:05Janna Levin?

  It was painful, though. It was painful. So, the idea is really...

• 1:17:08Neil deGrasse Tyson?

  Oh, I can't wait to read it.

• 1:17:12Janna Levin?

  What they're doing there is they're saying, you know, this is kind of relevant to your question earlier about cosmology. The Big Bang singularity looks a lot like kind of the inverse of a black hole singularity. So, instead of everything falling out of the universe, uh, falling, you know, out of, out of the black hole, everything in the Big Bang is coming out of the singularity. And so, they were like, well, maybe I should just sew these two things together. And the interesting thing is mathematically, in this very formal, technical book, they can prove that the spacetimes mathematically can be sewn together flawlessly. And that's not a given.

• 1:17:44Chuck Nice?

  Wow.

• 1:17:44Janna Levin?

  Right? And it's beautiful, and you can sew them together. That's, so they said, oh, maybe when you start to go into the singularity, you're actually blown out into a new Big Bang. And that's another beautiful thing, is that the black holes might be small on the outside, in the way we've described, but they're much, much bigger on the inside.

• 1:18:01Chuck Nice?

  Like the TARDIS.

• 1:18:02Janna Levin?

  It's the TARDIS. It's Doctor Who's TARDIS. And they can be as big as an entire universe on the inside. And that's a beauty of curved spacetime allows you that kind of trickery. So, it doesn't mean that we have a prediction that that's what happens. It's just suggestive that the math permits it.

• 1:18:22Neil deGrasse Tyson?

  All right, let's get even more freaky before we close this out. So, you mentioned wormholes possibly being the fabric of a black hole. But how about the wormholes in this science fiction sense? Where... I'm over here, but now I walk through a portal and then I'm over there. As is displayed in the Marvel superhero Doctor Strange. Or of course, Rick and Morty, right? Okay? So much better. Yeah, okay. So is there anything that prevents that? Because clearly, if that can exist, it's going to be using some Einstein theories.

• 1:18:58Janna Levin?

  Yeah, so wormholes are again, a mathematical possibility. That we don't understand how they're possible. It might be like black holes before we realized they were real. So we don't understand what source of matter or energy will keep that throat open. They tend to want to collapse. And so we don't know of any form of matter or energy in the actual universe that keeps wormholes open and allows us to transmit.

• 1:19:22Neil deGrasse Tyson?

  It's got to be like a negative gravity.

• 1:19:24Janna Levin?

  But they're totally fine. It's got to be kind of a negative gravity. We don't know of anything. But look, there's dark matter, dark energy, and we don't know what those are either. So nobody should say, we will never discover a form of energy that can keep a wormhole open. But, but, you know, who knows? Maybe it will be related to the dark energy or the dark matter. So it is perfectly fine to attach spacetime with these little bridges. That part's completely easy to understand.

• 1:19:48Neil deGrasse Tyson?

  Nothing wrong with that.

• 1:19:49Janna Levin?

  Nothing wrong with that.

• 1:19:50Neil deGrasse Tyson?

  All right, last bit, Jana, before we call this out. In the movie Interstellar, one of the more poignant, stupefying scenes was when the spaceship was orbiting a black hole. I think they call it Gargantua. And there were a, a, a black hole that had a planet. And some of the crew went down to the planet. Closer to the black hole. Because the planet is orbiting the black hole. And they stayed far away. They had completely different timelines. Could tell me about time dilation around a black hole?

• 1:20:21Janna Levin?

  Yeah, we actually even see the effect around the Earth. The, the rate at which literally our clocks tick.

• 1:20:29Janna Levin?

  Is slower closer to the earth than it is further away. So when we communicate with satellites, there's actually the additional effect of the speed of the satellite, which I do believe causes a greater dilation. But we do see that there's-

• 1:20:42Neil deGrasse Tyson?

  Well, you can run the math. It's actually less than the gravity.

• 1:20:45Janna Levin?

  It is less than the gravity? So it happens, but around a black hole, it's so extreme that this is part of the rotation of space and time that we were just discussing. So if one astronaut stays far from the black hole, they both have perfectly calibrated clocks, the other astronaut travels near and near in the black hole. And as they do, it's almost as though they're rotating in spacetime such that their clocks are running slower and slower and slower relative to the person further away. When you hit that horizon, technically, you've rotated all the time away. That's why the center of the black hole is in the future's time direction and not in the space direction. I'm literally not expecting anyone to understand that.

• 1:21:26Chuck Nice?

  Right.

• 1:21:26Janna Levin?

  Like, nobody.

• 1:21:28Neil deGrasse Tyson?

  Well, look, to what happened, if you didn't see the scene, those 11 of you who didn't see the movie-

• 1:21:34Janna Levin?

  Right.

• 1:21:34Neil deGrasse Tyson?

  Then security should have removed already.

• 1:21:36Janna Levin?

  Right, so the astronaut who stays far away-

• 1:21:38Neil deGrasse Tyson?

  So they have astronauts up here, when we're down on the planet with them, and 20 minutes goes by-

• 1:21:45Janna Levin?

  Right.

• 1:21:46Neil deGrasse Tyson?

  And then they beam, or I forgot how they got back up to the ship-

• 1:21:49Janna Levin?

  Right.

• 1:21:49Neil deGrasse Tyson?

  And the folks on the ship are gray-

• 1:21:51Janna Levin?

  20 years.

• 1:21:52Neil deGrasse Tyson?

  And they age 20 years. And they're like, "Why isn't your call?"

• 1:21:58Janna Levin?

  Yeah, they've spent 20 years. And this is a real effect. We literally see the effect even around the earth. We correct, our phones correct for the relativistic time dilation-

• 1:22:10Chuck Nice?

  Wait, wasn't there an experiment though? Where they took atomic clocks and they did exactly that, where one-

• 1:22:15Neil deGrasse Tyson?

  Oh, that's 40 years ago.

• 1:22:16Chuck Nice?

  Yeah.

• 1:22:17Neil deGrasse Tyson?

  Yeah. Keep up with the century here.

• 1:22:19Chuck Nice?

  No, I'm sorry, but it's exactly what you're saying. It's proven because there's an actual experiment.

• 1:22:25Janna Levin?

  Well, it's also proven because we know that there are subatomic particles which have incredibly short lifetimes. If they're just sitting in your laboratory, they decay in a fraction of a second, but you boost them near the speed of light and they will appear to live for minutes.

• 1:22:37Neil deGrasse Tyson?

  Wow.

• 1:22:38Janna Levin?

  It's real.

• 1:22:38Neil deGrasse Tyson?

  Wait, so you were saying your cell phones, so that's, the origin of that is the- GPS satellites. So the GPS satellites are in a different gravitational field from us. So their clocks take at a different rate about because of general relativity. Yet, all of our clocks are synchronized and perfect because we pre-correct the GPS time for general relativity so that it's correct on Earth time. That's science.

• 1:23:15Neil deGrasse Tyson?

  All right, so, yes.

• 1:23:19Neil deGrasse Tyson?

  So let me get some, just some closing thoughts. Jenny, what can you tell us just about life, the universe, and everything? Your, your, your, your career being emboldened by J W E S T?

• 1:23:32Speaker 02

  I'll tell you, my husband always wants to know what's inside a black hole. So now I'm gonna go home and tell him I learned what's inside a black hole.

• 1:23:41Neil deGrasse Tyson?

  Okay, Jenna.

• 1:23:43Janna Levin?

  Closing thoughts? Well, hmm. Um, I do think it is quite amazing that black holes are like fundamental particles. They're fundamental to the universe in a way that nothing else is, that we don't really understand. So when the universe was created, it might have made black holes in the same way it made electrons. They might be a fundamental property of the universe. And little quantum black holes.

• 1:24:09Neil deGrasse Tyson?

  Exotic thing that'll need some telescopes.

• 1:24:10Janna Levin?

  We think of them as collapsed dead stars. And that is a brilliant way that nature thought of to make black holes, just kill off some stars. But they, they actually are not dead stars. That's not their, that's just one vehicle for making them. And, um, and we do think that black holes might have been created in the early universe. And they were, uh, like as heavy as a little pile of sesame seeds. But they were smaller than a proton. And, um, and those quantum black holes would have evaporated away like firecrackers. But they are, they are a very profound and fundamental property of the universe.

• 1:24:47Neil deGrasse Tyson?

  Alright, so Chuck, would you, do you have a?

• 1:24:51Chuck Nice?

  I do, I have several closing thoughts. But really, I am so proud to see a theater full of people as we discuss these mind-expanding principles and we talk about things that are so incredible with respect to our being and the fact that we can look up and look out and wonder. And the fact that you are here gives me hope for this entire stupid rock that we are all floating on.

• 1:25:31Neil deGrasse Tyson?

  So I'd like maybe to offer some closing thoughts myself. That one of the things we've noticed about the universe is that every time a new telescope comes online, a new telescope, not just that it's brand-new and shiny, but that it was conceived to access the universe by looking through a window that previously had not been opened. By looking through a window that we didn't even know was there. At some point, someone has to say, "I think there's something on the other side of this window, because I just discovered this new window, and no one's looked through it before." So, we gather funds, we propose, it gets peer-reviewed,

• 1:26:16Neil deGrasse Tyson?

  and the telescopes get developed, once again, by engineers to empower the science that we have. And what a journey this has been. We are in the centennial decade of the discovery of quantum physics. That was in the 1920s. And you know what actually happened? 97 years ago, Edwin Hubble discovered that our galaxy wasn't the only galaxy in the universe. That the fuzzy things that half of the Messier had found were whole other galaxies. In a sense, island universes, they were poetically referenced.

• 1:26:58Neil deGrasse Tyson?

  He was using the biggest telescope available in the day.

• 1:27:04Neil deGrasse Tyson?

  And so every time we do this, our minds are not only blown, when we put it back together, our minds have actually expanded. And we learn more and more about our place in the universe. So one of the greatest gifts to civilization are the discoveries in astrophysics, because we all look up at night. When the stars call to you, and they call to me, I know that maybe you don't become an astrophysicist, but if you walk out at night and it's not cloudy and the moon isn't out, those stars are screaming.

• 1:27:48Neil deGrasse Tyson?

  And you've experienced this, not in the northeast. You visit some... Yeah. All right. You go someplace, okay?

• 1:28:01Neil deGrasse Tyson?

  You know what I'm talking about. The universe calls to you. So I would claim that the study of the universe, opening up these great portals, not only the theoretical portals, but the technological portals to the universe, that there's no greater source of a cosmic perspective than all the new understandings that come down the pipe that tell us how big the universe is, how old the universe is. And then, in a way, looking back on Earth, it makes Earth all the more precious. In the vastness of the universe,

• 1:28:46Neil deGrasse Tyson?

  this is the only place we've got. Are we the shepherds we need to be to assure our own survival on our own planet? So that the next generations can be proud of the decisions we've made, rather than embarrassed by the decisions we didn't. And black holes are just another part of that glorious story. A little more obscure, really fun, good fodder for a science fiction storytelling. But I wouldn't have it any other way. That is a cosmic perspective.

• 1:29:30Neil deGrasse Tyson?

  That's it. StarTalk at the Kestwick Theater, Philadelphia.

• 1:29:37Neil deGrasse Tyson?

  Thank you.

• 1:29:39Neil deGrasse Tyson?

  Jenna Levin.

• 1:29:42Neil deGrasse Tyson?

  Jenny Green.

• 1:29:45Neil deGrasse Tyson?

  Chuck Nice.